This invention relates to an ion selective electrode device and a flowthrough type ion analyzing apparatus utilizing the same.
Ion selective electrodes which are combined to constitute an electrode device are generally used to electrochemically detect the concentration of ions of each type contained in sample solution. Various types of ion selective electrodes have been proposed. For example, an ion selective electrode having the following structure is disclosed in Japanese Unexamined (KOKAI) patent application No. 55-154454 (application No. 54-61463). A lead wire for voltage detection is connected to a central portion of an outer surface of a tubular metal substrate having a through hole at its center. Ion sensitive layers are solvent-welded on the inner and outer surfaces of the metal substrate. When a sample solution flows into the through hole to bring ions in the sample solution into contact with the inner ion sensitive layer, a predetermined single electrode potential difference is detected.
In order to independently analyze several types of ion, ion selective electrodes are detachably coupled to each other at predetermined intervals through a connecting tube.
The conventional ion selective electrode of this type and an ion analyzing apparatus using such an ion selective electrode have the following disadvantages.
Since the sample is brought into contact with the metal substrate through the ion sensitive layer, heat dissipation from the sample to the metal substrate is increased, and an ion concentration of the sample cannot be accurately measured (to be described in detail later).
Since a plurality of electrodes are coupled in series with each other through the connecting tube to constitute an electrode device, a concave or stepped portion is formed in a flow path along which the sample flows. As a result, an uniform sample flow is disturbed, resulting in a disadvantage.
Furthermore, since the substrate is made of a metal, precise machining techniques must be employed to form a small-diameter through hole therethrough.
It is a first object of the present invention to provide an ion selective electrode device having a low heat capacity so as to prevent a decrease in temperature of an ion sample while ion concentration is being measured.
It is a second object of the present invention to provide an ion selective electrode device which may be easily manufactured using printed wiring techniques without requiring precise metal working techniques.
It is a third object of the present invention to provide an ion selective electrode device which has no obstacle such as a projection to disturb an uniform sample flow in a flow path for ion measurement.
It is a fourth object of the present invention to provide an ion selective electrode device wherein a plurality of ion selective electrodes are constructed in one body.
It is a fifth object of the present invention to provide an ion analyzing apparatus using such an ion selective electrode device.